Long-Distance Water Transport Under Controlled Transpirational Conditions: Minimal-Invasive Investigations by Means of Pressure Probes and NMR Imaging

Herbaceous plants exhibit complex reaction patterns as a response to changes in environmental factors such as light intensity, relative humidity, temperature and root water-supply. The reactions of volume flows and hydrostatic pressures within the intact plant can only be described in an authentic way if minimal- and non-invasive methods are used for investigation. This review article highlights some aspects on the correlation of xylem volume flows and corresponding hydrostatic pressures, with special emphasis put on the role of the water supply to the roots. From these studies it can be concluded that the tissue cells play an important role in determining and maintaining xylem pressures.